From 4615ec4eaf5064262829d12a040c8de64290aad7 Mon Sep 17 00:00:00 2001
From: Joe Rafaniello <jrafanie@redhat.com>
Date: Fri, 15 May 2015 13:57:38 -0400
Subject: [PATCH] Dup the @names hash when the Headers hash is copied.

Without this change, a connection's header and each request's header
all reference the same `@names` hash object so any request that modified
it via delete or other mutating methods, would affect the headers of other
requests and the connection.

In [travis.rb](https://github.com/travis-ci/travis.rb/blob/9b3eb05542e37b99a40ab89c0e861019664c15d7/lib/travis/client/session.rb#L206-209), it was doing:

```ruby
  connection.public_send(verb, url, *args) do |request|
    next if request.path !~ /^https?:/ or request.path.start_with? api_endpoint
    request.headers.delete("Authorization")
  end
```

This caused the headers of multiple requests (and the connection) to share
the same `@names` hash object, resulting in `@names` and the Header hash
to go out of sync:

thing| @names | Header
--- | --- | --- | ---
connection | no Authorization | Has Authorization
request 1 | no Authorization | no Authorization
request 2 | no Authorization | Has Authorization

Because Headers uses the `@names` to determine if it `includes?` a key or
if there's a key to `delete`, you would have Authorization in the headers
but it wouldn't be removed because `@names` didn't have it.
---
 lib/faraday/utils.rb    | 12 ++++++++++++
 test/connection_test.rb | 14 ++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/lib/faraday/utils.rb b/lib/faraday/utils.rb
index 1cd6526a..c3118fb3 100644
--- a/lib/faraday/utils.rb
+++ b/lib/faraday/utils.rb
@@ -17,6 +17,12 @@ module Faraday
         self.update(hash || {})
       end
 
+      # on dup/clone, we need to duplicate @names hash
+      def initialize_copy(other)
+        super
+        @names = other.names.dup
+      end
+
       # need to synchronize concurrent writes to the shared KeyMap
       keymap_mutex = Mutex.new
 
@@ -101,6 +107,12 @@ module Faraday
             end
           }
       end
+
+      protected
+
+      def names
+        @names
+      end
     end
 
     # hash with stringified keys
diff --git a/test/connection_test.rb b/test/connection_test.rb
index e1647367..8ef4da9e 100644
--- a/test/connection_test.rb
+++ b/test/connection_test.rb
@@ -200,6 +200,20 @@ class TestConnection < Faraday::TestCase
     assert_equal "http://sushi.com/nigiri?a=1&b=2&c=3", url.to_s
   end
 
+  def test_request_header_change_does_not_modify_connection_header
+    connection = Faraday.new(:url => "https://asushi.com/sake.html")
+    connection.headers = { "Authorization"=>"token abc123" }
+
+    request = connection.build_request(:get)
+    request.headers.delete("Authorization")
+
+    assert_equal connection.headers.keys.sort, ["Authorization"]
+    assert connection.headers.include?("Authorization")
+
+    assert_equal request.headers.keys.sort, []
+    assert !request.headers.include?("Authorization")
+  end
+
   def test_env_url_parses_url_params_into_query
     uri = env_url("http://sushi.com/sake.html", 'a[b]' => '1 + 2')
     assert_equal "a%5Bb%5D=1+%2B+2", uri.query